Salmonella FliR and FlhB are membrane proteins necessary for flagellar export. In Clostridium a fliR-flhB fusion gene exists. We constructed a similar Salmonella fusion gene which is able to complement fliR, flhB, and fliR flhB null strains. Western blotting revealed that the FliR-FlhB fusion protein retains the FlhB protein's cleavage properties. We conclude that the FliR and FlhB proteins are physically associated in the wild-type Salmonella basal body, probably in a 1:1 ratio.